Gametes of both sexes are highly specialized cells with the unique function of transmitting haploid parental genomes and factors required for early embryonic development to the subsequent generation. Identifying gene products specifically expressed in gametes is the first step to understanding the gamete "transcriptome". From 1998-2000, we received NICHD funding for a pilot grant (R03 HD37231) entitled "Identification and Analysis of Novel Ovarian Genes". During the last 4 years, we used PCR-based subtraction, in silico subtraction, and genome database mining to identify over 20 novel gonad-expressed genes and we selected three intriguing oocyte-specific genes to study in depth for this proposal. The unifying goal of this R01 proposal is to determine how these 3 key expressed genes relate to oocyte and embryonic developmental potential. To provide insights into the roles of these 3 genes in development and the processes that ultimately control fertility, we will define their biochemical and physiological properties using strategies such as yeast two-hybrid screens and the generation of knockout mouse models. Over the last decade, we have generated numerous transgenic and knockout mice that have reproductive defects, including knockout mice lacking growth differentiation factor-9, bone morphogenetic protein 15, pentraxin 3, follicle stimulating hormone, alpha-inhibin, activin receptor type II, superoxide dismutase 1, gamma-glutamyl transpeptidase, SMAD5, cyclin A1, and oxytocin. The utility of mouse models in investigating gene function in vivo is unparalleled. Together, the abilities to discover novel genes and define their functions in mouse models provide powerful means to study the molecular processes of mammalian gametogenesis. Structural analyses and functional data from knockout studies will enable us to place these gene products in biological pathways and gain insight into oocyte physiology. Compromised fertility in knockout models lacking these oocyte-specific genes would demonstrate that these proteins are potential contraceptive targets and possibly mutated in infertile women.